1. Technical Field
The present disclosure relates to a vehicular lamp that emits light so as to form a low-beam light distribution pattern, and more particularly, to a so-called projector type vehicular lamp.
2. Related Art
In a projector type vehicular lamp, a projection lens is disposed on the optical axis of the lamp extending in the longitudinal direction of a vehicle, a light source is disposed on the rear side of a rear focal point of the projection lens, and the light emitted from the light source is reflected by the reflector so as to be concentrated on the projection lens.
For example, JP-A-2003-288805 describes a related art projector type vehicular lamp in which a shade, which blocks a part of the light reflected from a reflector, is disposed such that the upper edge of the shade is disposed near the rear focal point of a projection lens, and thus light is emitted to form a low-beam light distribution pattern.
In the related art projector type vehicular lamp, if the central axis of the reflector is moved parallel to the optical axis of the lamp toward the opposite lane, a position where the light, which is emitted from the light source and reflected from the reflector, passes through the rear focal plane of the projection lens may be displaced toward the opposite lane as a whole as compared to when the central axis of the reflector is not moved parallel to the optical axis of the lamp. Accordingly, it may be possible to displace a low-beam light distribution pattern, which is formed as the reverse image of a light source image formed on the rear focal plane of the projection lens, toward the own lane, i.e., the lane in which the vehicle is traveling, as a whole as compared to when the central axis of the reflector is not moved parallel to the optical axis of the lamp. Accordingly, it may be possible to form a hot zone, i.e., an area having a high luminosity, of the low-beam light distribution pattern at a position that is close to the own lane in the forward direction of the lamp.
However, the above-mentioned structure has the following disadvantages.
That is, if the light reflected from the reflector enters the projection lens as a convergent light flux, the incident angle of the light, which is reflected from the end area of the reflecting surface of the reflector corresponding to the opposite lane and which enters the projection lens is significantly large on the front surface of the projection lens. Thus, the light is totally reflected from the front surface and is not emitted forward. Accordingly, it is difficult to effectively use the luminous flux of the light source.
In this case, the light, which is reflected from the end area of the reflecting surface of the reflector corresponding to the opposite lane, becomes the light that forms the diffusion area of the low-beam light distribution pattern corresponding to the own lane. However, since this light is not obtained, the diffusion angle of the low-beam light distribution pattern corresponding to the own lane is decreased.